”We are confronting yet another mass shooting — and today, it happened on a military installation in our nation’s capital,” the president said, as he pressed forward with a speech on the five-year anniversary of the economic crisis. “Obviously, we’re going to be investigating thoroughly what happened, as we do so many of these shootings, sadly, that have happened, and do everything that we can to try to prevent them.”

The newest mass shooting, like earlier ones at Virginia Tech, Tucson, Aurora and Newtown, was carried out by a well-armed lone gunman, police said Monday night.

But comparisons between the attack last December at Sandy Hook Elementary and Monday’s violence in Washington present the White House and gun control advocates with a stark question and a grim reality: If the murder of 20 first graders in their Connecticut grade school wasn’t enough to pass a bill, how likely is it the deaths of 12 adults at a Navy base change the result?

The latest tragedy is all too fresh, but the politics are the same. Last April, a Senate filibuster effectively blocked the effort to expand background checks and ban the sale of assault weapons and large-capacity ammunition magazines. Even if it had passed, it seemed doomed in the GOP-led House. And since then, gun rights advocates have increased pressure on lawmakers, successfully recalling two Democratic Colorado state senators who supported gun control measures.

Tuesday, Sen. Joe Manchin (D-W.Va.), who sponsored the compromise background checks plan, said he wouldn’t bring it back up post-Navy Yard until he can get the support of five more senators.

Monday’s events left advocates calling for more action from the White House and Congress, with some arguing that the series of shootings was having a cumulative effect on the public even if the latest spree seemed unlikely to be as nationally searing as Sandy Hook.

“I think the country and indeed the president have reached the tipping point not because of one mass shooting but because of an aggregate drip, drip, drip of more and more mass shootings,” said Mark Glaze of Mayors Against Illegal Guns — a group New York Mayor Michael Bloomberg formed to do battle with the National Rifle Association over the issue. “Every time this happens, it throws additional fuel on a fire already blazing pretty high.”

Dan Gross of the Brady Campaign to Prevent Gun Violence said that if people thought Newtown itself would be so transformative that it would vault gun legislation into law, they were mistaken.

“No one tragedy — no matter how horrible — is going to be enough to create the sustained public will that’s necessary to create change on this issue,” he said.

White House Press Secretary Jay Carney said during a briefing Monday afternoon that it was too soon to talk about specific legislative responses while the facts of what happened at the Navy Yard were still being sorted out.

“It would be inappropriate to try to put in context something about which we have so few facts,” Carney said, while reiterating Obama’s support for “common-sense measures” to cut down on gun violence. “It is far too early to say anything about who did this and the broader meaning of it.”

After the White House push for background checks died in the Senate in April, Vice President Joe Biden told religious and law enforcement groups that he and Obama would travel the country to stump for gun control measures. But that effort never materialized and Senate Judiciary Chairman Patrick Leahy (D-Vt.) said this summer that the legislation would not come up again this year.

Gun control advocates said they hope the White House and the president won’t hesitate for long before diving back into the legislative battle.

“I think it’s appropriate for the White House to wait until we know what happened, but at some point soon we will time to think hard about whether some senators who voted against what 90 percent of the public wants — expanded background checks — have some explaining to do,” Glaze said.

“While this issue is so prominent and in front of the American public, it is an appropriate time to make another push,” Gross said.

Gross noted that in the 1990s, the Brady Bill “took six votes, over seven years and three Congresses to pass.”

Despite the recent spate of mass shootings, the public does not seem as exercised about the issue as it was in the 1990s when those incidents took place against a backdrop of widespread concern about violent crime. Murder rates have dropped by more than half in many parts of the country.

“From the 70s through the early 90s, the crime rate was going up steadily and the feeling was this is inexorable and is only going to get worse,” said Jim Kessler of the Democratic centrist group Third Way. “It was the top of mind issue. Mike Dukakis arguably lost the presidential election on the basis of how he handled one, single criminal case. That’d be unimaginable today.”